Question
Question: Find out the major product for the above reaction. [Main July 28, 2022] ...
Find out the major product for the above reaction. [Main July 28, 2022]
A
(a)
B
(b)
C
(c)
D
(d)
Answer
a
Explanation
Solution
The reaction proceeds via iodolactonization, forming a 5-membered iodo-lactone (γ-lactone) as the major intermediate due to favored 5-membered ring formation. The carboxylate oxygen attacks C1 of the double bond, placing iodine on C2. Subsequent dehydroiodination (elimination of HI) by pyridine and heat leads to the formation of a double bond between C1 and C2, resulting in an α,β-unsaturated lactone. This product matches option (a).